Hydrant cap leak detector with oriented sensor

ABSTRACT

A nozzle cap includes a cap body defining a cap axis, the cap body defining a circumferential wall extending circumferentially around the cap axis; and a vibration sensor including a shaft, the shaft defining a first end and a second end, the first end attached to the circumferential wall, the cap axis positioned closer to the second end than to the first end.

REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.17/079,642, filed Oct. 26, 2020, which is a divisional of U.S.application Ser. No. 16/121,136, filed Sep. 4, 2018, which issued intoU.S. Pat. No. 10,859,462 on Dec. 8, 2020, each of which is herebyspecifically incorporated by reference herein in its entirety.

TECHNICAL FIELD

This disclosure relates to fire hydrants. More specifically, thisdisclosure relates to a vibration sensor for detecting leaks in a watersystem connected to a fire hydrant.

BACKGROUND

Fire hydrants are commonly connected to fluid systems, such as municipalwater infrastructure systems and water mains, through stand pipes.Because these fluid systems are typically partially or entirely locatedunderground, it can be difficult to detect leaks within the fluidsystems. Additionally, it can be difficult to access these fluid systemsfor monitoring. Fire hydrants can provide convenient above-ground accessto the fluid systems. Leaks within the fluid systems can send vibrationsthrough the fluid system and up stand pipes to the fire hydrants. Thesevibrations propagating through the stand pipes and fire hydrants can bemonitored to detect leaks within the connected fluid system. However,fire hydrants can be subjected to other sources of vibration such aswind, rain, ambient noise from loud passing vehicles, or direct contactsuch as pedestrians bumping into fire hydrants or bicyclists leaningtheir bicycles against fire hydrants. These sources of background noisecan trigger false alarms or make it more difficult for a potential leakto be detected.

SUMMARY

It is to be understood that this summary is not an extensive overview ofthe disclosure. This summary is exemplary and not restrictive, and it isintended to neither identify key or critical elements of the disclosurenor delineate the scope thereof. The sole purpose of this summary is toexplain and exemplify certain concepts of the disclosure as anintroduction to the following complete and extensive detaileddescription.

Disclosed is a nozzle cap comprising a cap body defining a cap axis, thecap body defining a circumferential wall extending circumferentiallyaround the cap axis; and a vibration sensor comprising a shaft, theshaft defining a first end and a second end, the first end attached tothe circumferential wall, the cap axis positioned closer to the secondend than to the first end.

Also disclosed is a hydrant assembly comprising a fire hydrantcomprising a barrel and a nozzle extending outwards from the barrel; anda nozzle cap comprising a cap body mounted on the nozzle, the cap bodydefining a cap axis, the cap body defining a circumferential wallextending circumferentially around the cap axis; and a vibration sensorcomprising a shaft, the shaft defining a first end and a second end, thefirst end attached to the circumferential wall, the cap axis positionedcloser to the second end than to the first end.

Various implementations described in the present disclosure may includeadditional systems, methods, features, and advantages, which may notnecessarily be expressly disclosed herein but will be apparent to one ofordinary skill in the art upon examination of the following detaileddescription and accompanying drawings. It is intended that all suchsystems, methods, features, and advantages be included within thepresent disclosure and protected by the accompanying claims. Thefeatures and advantages of such implementations may be realized andobtained by means of the systems, methods, features particularly pointedout in the appended claims. These and other features will become morefully apparent from the following description and appended claims, ormay be learned by the practice of such exemplary implementations as setforth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and components of the following figures are illustrated toemphasize the general principles of the present disclosure. The drawingsare not necessarily drawn to scale. Corresponding features andcomponents throughout the figures may be designated by matchingreference characters for the sake of consistency and clarity.

FIG. 1 is a perspective view of a hydrant assembly in accordance withone aspect of the present disclosure.

FIG. 2 is a perspective rear view of a nozzle cap of the hydrantassembly of FIG. 1 .

FIG. 3 is a front view of the nozzle cap of FIG. 2 shown with a capcover 280 of the nozzle cap removed.

FIG. 4 is a perspective view of one example aspect of a vibration sensorin accordance with one aspect of the present disclosure.

FIG. 5 is a front detail view of the hydrant assembly of FIG. 1 focusingon the nozzle cap with the cap cover shown in transparency and theunderlying components shown in dashed lines.

FIG. 6 is a front detail view of the hydrant assembly of FIG. 1 focusingon the nozzle the nozzle cap, which demonstrates various potentialpositions for the vibration sensor of FIG. 4 .

FIG. 7 is a cross-sectional side view of a barrel and the nozzle cap ofFIG. 1 taken along line 7-7 shown in FIG. 6 .

DETAILED DESCRIPTION

The present disclosure can be understood more readily by reference tothe following detailed description, examples, drawings, and claims, andthe previous and following description. However, before the presentdevices, systems, and/or methods are disclosed and described, it is tobe understood that this disclosure is not limited to the specificdevices, systems, and/or methods disclosed unless otherwise specified,and, as such, can, of course, vary. It is also to be understood that theterminology used herein is for the purpose of describing particularaspects only and is not intended to be limiting.

The following description is provided as an enabling teaching of thepresent devices, systems, and/or methods in its best, currently knownaspect. To this end, those skilled in the relevant art will recognizeand appreciate that many changes can be made to the various aspects ofthe present devices, systems, and/or methods described herein, whilestill obtaining the beneficial results of the present disclosure. Itwill also be apparent that some of the desired benefits of the presentdisclosure can be obtained by selecting some of the features of thepresent disclosure without utilizing other features. Accordingly, thosewho work in the art will recognize that many modifications andadaptations to the present disclosure are possible and can even bedesirable in certain circumstances and are a part of the presentdisclosure. Thus, the following description is provided as illustrativeof the principles of the present disclosure and not in limitationthereof.

As used throughout, the singular forms “a,” “an” and “the” includeplural referents unless the context clearly dictates otherwise. Thus,for example, reference to “an element” can include two or more suchelements unless the context indicates otherwise.

Ranges can be expressed herein as from “about” one particular value,and/or to “about” another particular value. When such a range isexpressed, another aspect includes from the one particular value and/orto the other particular value. Similarly, when values are expressed asapproximations, by use of the antecedent “about,” it will be understoodthat the particular value forms another aspect. It will be furtherunderstood that the endpoints of each of the ranges are significant bothin relation to the other endpoint, and independently of the otherendpoint.

For purposes of the current disclosure, a material property or dimensionmeasuring about X or substantially X on a particular measurement scalemeasures within a range between X plus an industry-standard uppertolerance for the specified measurement and X minus an industry-standardlower tolerance for the specified measurement. Because tolerances canvary between different materials, processes and between differentmodels, the tolerance for a particular measurement of a particularcomponent can fall within a range of tolerances.

As used herein, the terms “optional” or “optionally” mean that thesubsequently described event or circumstance can or cannot occur, andthat the description includes instances where said event or circumstanceoccurs and instances where it does not.

The word “or” as used herein means any one member of a particular listand also includes any combination of members of that list. Further, oneshould note that conditional language, such as, among others, “can,”“could,” “might,” or “may,” unless specifically stated otherwise, orotherwise understood within the context as used, is generally intendedto convey that certain aspects include, while other aspects do notinclude, certain features, elements and/or steps. Thus, such conditionallanguage is not generally intended to imply that features, elementsand/or steps are in any way required for one or more particular aspectsor that one or more particular aspects necessarily include logic fordeciding, with or without user input or prompting, whether thesefeatures, elements and/or steps are included or are to be performed inany particular aspect.

Disclosed are components that can be used to perform the disclosedmethods and systems. These and other components are disclosed herein,and it is understood that when combinations, subsets, interactions,groups, etc. of these components are disclosed that while specificreference of each various individual and collective combinations andpermutation of these may not be explicitly disclosed, each isspecifically contemplated and described herein, for all methods andsystems. This applies to all aspects of this application including, butnot limited to, steps in disclosed methods. Thus, if there are a varietyof additional steps that can be performed it is understood that each ofthese additional steps can be performed with any specific aspect orcombination of aspects of the disclosed methods.

Disclosed is a hydrant assembly and associated methods, systems,devices, and various apparatus. The hydrant assembly can comprise a firehydrant and a vibration sensor. It would be understood by one of skillin the art that the disclosed hydrant assembly is described in but a fewexemplary aspects among many. No particular terminology or descriptionshould be considered limiting on the disclosure or the scope of anyclaims issuing therefrom.

FIG. 1 is a perspective view of a hydrant assembly 100 comprising a firehydrant 110 and a vibration sensor 380 (shown in FIG. 3 ) in accordancewith one aspect of the present disclosure. The fire hydrant 110 cancomprise a barrel 120, a nozzle cap 150, and a bonnet 180. The barrel120 can define a top barrel end 122 and a bottom barrel end 124 disposedopposite from the top barrel end 122. The barrel 120 can besubstantially tubular, and the barrel 120 can define a barrel axis 101extending from the top barrel end 122 to the bottom barrel end 124. Inthe present aspect, the barrel axis 101 can be substantially verticallyaligned wherein the barrel axis 101 is aligned with the force ofgravity.

The barrel 120 can comprise a top flange 126 disposed at the top barrelend 122 and a base flange 128 disposed at the bottom barrel end 124. Thebase flange 128 can be fastened to a stand pipe flange 199 of a standpipe 198 of a fluid system (not shown), such as a water main for exampleand without limitation. The base flange 128 can be fastened to the standpipe flange 199 by a plurality of fasteners 130. A bonnet flange 182 ofthe bonnet 180 can be attached to the top flange 126 of the barrel 120,such as with a plurality of fasteners (not shown) similar to thefasteners 130. The bonnet 180 can comprise an operation nut 184, or “opnut”, which can be rotated to open and close a main valve (not shown)positioned at the bottom barrel end 124 or below in the stand pipe 198in order to respectively supply or cut off pressurized water flow to thefire hydrant 110.

The barrel 120 can define one or more nozzles 140 a,b. The nozzle cap150 can be screwed onto the nozzle 140 a to seal the nozzle 140 a. Withthe nozzle cap 150 sealing the nozzle 140 a, pressurized water cannotescape through the nozzle 140 a when the main valve (not shown) is in anopen position. The nozzle cap 150 can define a cap nut 152 which can beturned, such as with a wrench, to tighten or loosen the nozzle cap 150on the nozzle 140 a.

FIG. 2 is a perspective rear view of the nozzle cap 150 of the firehydrant 110 of FIG. 1 . The nozzle cap 150 can comprise a cap body 210and a cap cover 280. The cap body 210 can define a first body end 212and a second body end 214 disposed opposite from the first body end 212.The cap cover 280 can be attached to the first body end 212 of the capbody 210. The cap body 210 can define a threaded bore 216 extending intothe cap body 210 from the second body end 214 to an inner wall 220 ofthe cap body 210. The threaded bore 216 can define a cap axis 201 of thecap body 210, and the cap axis 201 can extend from the first body end212 to the second body end 214.

The threaded bore 216 can define internal threading 218, and thethreaded bore 216 can be screwed onto the nozzle 140 a (shown in FIG. 1) to mount the nozzle cap 150 on the nozzle 140 a by rotating the nozzlecap 150 about the cap axis 201. In the present aspect, the internalthreading 218 can be straight threading that does not taper from thesecond body end 214 towards the inner wall 220. In other aspects, theinternal threading 218 can be tapered threading that tapers from thesecond body end 214 towards the inner wall 220. A gasket 222 can bepositioned adjacent to the inner wall 220, and the gasket 222 can beconfigured to form a seal with the nozzle 140 a (shown in FIG. 1 ) whenthe nozzle cap 150 is screwed onto the nozzle 140 a in a sealedposition. As described below with respect to FIGS. 6 and 7 , the gasket222 can be selected based on its thickness, measured axially along thecap axis 201, to alter a rotational indexing of the nozzle cap 150relative to the nozzle 140 a.

FIG. 3 is a front view of the nozzle cap 150 of FIG. 1 with the capcover 280 (shown in FIG. 2 ) removed from the cap body 210. The cap body210 can define a cavity 310 extending inwards into the cap body 210 fromthe first body end 212 to the inner wall 220. In the present aspect, thecavity 310 can extend axially inward relative to the cap axis 201, shownextending out of the page. The inner wall 220 can separate the cavity310 from the threaded bore 216 (shown in FIG. 2 ). The cap body 210 candefine a circumferential wall 312 which partially encloses the cavity310 and extends circumferentially around the cavity 310 relative to thecap axis 201. A cavity opening 313 to the cavity 310 can be defined atthe first body end 212, and a cavity gasket 314 can extend around thecavity opening 313. The cavity gasket 314 can be configured to seal withthe cap cover 280 to enclose and seal the cavity 310.

The circumferential wall 312 can define external scallops 316 a,b. Theexternal scallops 316 a,b can extend radially inward into thecircumferential wall 312 relative to the cap axis 201. Each of theexternal scallops 316 a,b can respectively be enclosed by an antennacover 318 a,b, and an antenna strip 320 a,b can be enclosed within eachof the external scallops 316 a,b between the respective antenna cover318 a,b and the circumferential wall 312.

The nozzle cap 150 can comprise a battery pack 360 and a printed circuitboard (“PCB”) 362, each disposed within the cavity 310. The PCB 362 canbe attached to a mounting bracket 364 which can be secured within thecavity 310 by a pair of fasteners 366.

As shown, the nozzle cap 150 of the fire hydrant 110 can also comprisethe vibration sensor 380 of the hydrant assembly 100, and the vibrationsensor 380 can be disposed within the cavity 310. The vibration sensor380 can define a sensor axis 301 which can be perpendicular to the capaxis 201. The vibration sensor 380 can be attached to thecircumferential wall 312, and the vibration sensor 380 can extendradially inward from the circumferential wall 312 and into the cavity310 with respect to the cap axis 201.

The battery pack 360, the PCB 362, the vibration sensor 380, and theantenna strips 320 a,b can be connected together in electricalcommunication. The vibration sensor 380 can be configured to detectleaks within the fluid system (not shown) by monitoring vibrationstravelling up the stand pipe 198 (shown in FIG. 1 ) and through the firehydrant 110 (shown in FIG. 1 ) when the nozzle cap 150 is mounted on thenozzle 140 a (shown in FIG. 1 ). Vibration patterns within the fluidsystem can indicate the presence of leaks within the fluid system. Thevibration sensor 380 can produce voltage readings when the vibrationsensor 380 experiences vibrations. These voltage readings can beprocessed by the PCB 362 to determine whether leaks are present, and asignal can be transmitted outwards from the nozzle cap 150 by theantenna strips 320 a,b to convey whether leaks have been identifiedwithin the fluid system.

FIG. 4 is a perspective view of one example aspect of the vibrationsensor 380 of FIG. 3 wherein the vibration sensor 380 is a piezoelectricvibration sensor. Piezoelectric vibration sensors are described ingreater detail in U.S. Pat. No. 9,528,903, issued Dec. 27, 2016, whichis hereby incorporated by reference in its entirety.

The vibration sensor 380 can comprise a base 400, at least onepiezoelectric crystal 402, and a plurality of calibration masses 406.The calibration masses 406 can be distributed circumferentially aroundthe base 400. In the present aspect, the calibration masses 406 can beintegrally formed with the base 400; however in other aspects, thecalibration masses 406 can be separate components which can be attachedto the base 400, such as with a glue, adhesive, mastic, epoxy, oranother method such as welding, brazing, soldering, or any otherattachment method for example and without limitation. In the presentaspect, the calibration masses 406 can extend axially outward from eachside of the base 400 with respect to the sensor axis 301. A notch 432can be defined between each pair of adjacent calibration masses 406, andthe calibration masses 406 can vibrate independently from one another.

The piezoelectric crystal 402 can be attached to the base 400, and thepiezoelectric crystal 402 can be disposed radially inward from thecalibration masses 406 with respect to the sensor axis 301. In someaspects, an additional piezoelectric crystal (not shown) can be attachedto the opposite side of the base 400. In the present aspect, thepiezoelectric crystals 402 can be bonded to the base 400 with aconductive adhesive. In other aspects, the piezoelectric crystals 402can be attached to the base 400 through other suitable means such asdouble-sided tape, various glues, various coatings including elastomericand silicon coatings among others, pure adhesives, or by a fastener.

In the present aspect, a fastener 408 can extend through the base 400and piezoelectric crystals 402. The fastener 408 can define a threadedend 410, and a spacer 404 can be fit over the fastener 408 between thebase 400 and the threaded end 410. In the present aspect, the threadedend 410 can define a first sensor end 412 of the vibration sensor 380,and a second sensor end 414 can be defined by the calibration masses406, opposite from the first sensor end 412. The sensor axis 301 canextend through the fastener 408 and the vibration sensor 380 as a wholefrom the first sensor end 412 to the second sensor end 414.

The threaded end 410 can threadedly engage a threaded hole 780 (shown inFIG. 7 ) defined by the circumferential wall 312 (shown in FIG. 3 ) toattached the vibration sensor 380 to the cap body 210 (shown in FIG. 3). With the vibration sensor 380 attached to the cap body 210, and thenozzle cap 150 (shown in FIG. 3 ) attached to the nozzle 140 a (shown inFIG. 1 ), the vibration sensor 380 can detect vibrations from the fluidsystem (not shown) and convert the vibrations to a voltage signal. Whenthe vibration sensor 380 is exposed to vibrations, the calibrationmasses 406 can oscillate axially relative to the base 400 which canproduce internal stresses within the piezoelectric crystal 402. Stresseswithin the piezoelectric crystal 402 can produce a voltage signal whichcan then be interpreted by the PCB 362 (shown in FIG. 3 ) to determineif leaks are present within the fluid system.

FIG. 5 is a front detail view of the hydrant assembly 100 focusing onthe nozzle 140 a and the nozzle cap 150 with the cap cover 280 of thenozzle cap 150 shown in transparency with the underlying componentsshown in dashed lines. Experimentation has revealed that thesignal-to-noise ratio detected by the vibration sensor 380 is generallyoptimized when the sensor axis 301 is aligned with the barrel axis 101of the barrel 120 of the fire hydrant 110, such as when verticallyaligned relative to the direction of gravity as shown in the presentaspect.

The cap cover 280 can define indicia 501, which can align with thecircumferential placement of the vibration sensor around thecircumferential wall 312. For example, in the present aspect, thevibration sensor 380 can be positioned in a six-o-clock position whereinthe sensor axis 301 is vertically aligned, and the vibration sensor 380is positioned at the bottom of the nozzle cap 150. The indicia 501 canalso be positioned in the six-o-clock position so that the indicia 501is approximately centered over the vibration sensor 380. In the presentaspect, the indicia 501 can be the ECHOLOGICS logo which can beapproximately centered over the vibration sensor 380; however, in otheraspects, the indicia 501 can define any combination of words, numbers,and/or symbols to indicate the circumferential position of the vibrationsensor 380 along the circumferential wall 312. For example, in someaspects, the indicia could be a line extending across the cap cover 280which can be positioned parallel to the sensor axis 301 or an arrowindicating the preferred vertical alignment. Because a user cannot seeinto the cavity 310 in the present aspect, the indicia 501 can beconfigured to notify a user of the placement of the vibration sensor 380along the circumferential wall so that the nozzle cap 150 can beoptimally oriented when attaching the nozzle cap 150 to the nozzle 140a. In other aspects, some or all of the cap cover 280 can comprise atransparent material configured to provide a view of the orientation ofthe vibration sensor 380 within the cavity 310.

FIG. 6 is a front detail view of the hydrant assembly 100 focusing onthe nozzle 140 a and the nozzle cap 150 which demonstrates variouspotential positions 600 a—h for the vibration sensor 380 (shown in FIG.5 ) and the sensor axis 301, as shown by the dashed lines in the shapeof the vibration sensor 380. The cap cover 280 is shown without theindicia 501 (shown in FIG. 5 ) for clarity. The exemplary potentialorientations for the sensor axis 301 are shown as 301 a—d.

Sensor axis 301 a can correspond to the vertical orientations of thetwelve-o-clock position 600 a and the six-o-clock position 600 e. Inthese positions, the sensor axis 301 a is vertically aligned in parallelto the barrel axis 101 of the fire hydrant 110. These positionsgenerally provide an optimal signal-to-noise ratio, as described above.In these positions, an angle defined between the sensor axis 301 a andthe barrel axis 101 can equal zero degrees, and therefore, this angle isnot shown or labelled.

Sensor axis 301 c corresponds to the horizontal orientations of thethree-o-clock position 600 c and the nine-o-clock position 600 g. Inthese positions, the sensor axis 301 c is horizontally aligned, and thesensor axis 301 c can be perpendicular to the barrel axis 101. An angleA_(c) defined between the sensor axis 301 c and the barrel axis 101 canequal ninety degrees. Experimentation generally shows that thesignal-to-noise ratio is least desirable when the vibration sensor 380(shown in FIG. 5 ) is in a horizontal orientation with the sensor axis301 c perpendicular to the barrel axis 101, which is vertical.

The sensor axis 301 b corresponds to the positions 600 b,f, and thesensor axis 301 d corresponds to the positions 600 d,h. The sensor axes301 b,d can be oblique to the barrel axis 101. The sensor axis 301 b candefine an angle A_(b) with the barrel axis 101, and the sensor axis 301d can define an angle A_(d). In these positions, the angles A_(b),A_(d)can be acute angles measuring less than ninety degrees. In theseaspects, the signal-to-noise ratio is generally superior to that of thehorizontal orientations of positions 600 c,g but generally inferior tothe signal-to-noise ratio of the vertical orientations of positions 600a,e. The signal-to-noise ratio improves as the angles A_(b),A_(d)decrease to zero degrees, wherein the sensor axes 301 b,d align with thebarrel axis 101.

The demonstrated positions 600 a—h are merely exemplary and should notbe viewed as limiting. The vibration sensor 380 (shown in FIG. 5 ) canbe oriented at any angle around the cap axis 201, shown extending out ofthe page. The sensor axis 301 can be perpendicular to the cap axis 201regardless of potential orientation or rotational indexing of the nozzlecap 150.

Rotational indexing of the nozzle cap 150 relative to the nozzle 140 acan be primarily dictated by the torque required to form a seal betweenthe nozzle cap 150 and the nozzle 140 a via the gasket 222 (shown inFIG. 2 ). For example, in an aspect wherein the internal threading 218(shown in FIG. 2 ) of the threaded bore 216 (shown in FIG. 2 ) isright-handed threading, the nozzle cap 150 can be tightened onto thenozzle 140 a by rotating the nozzle cap 150 in a clockwise directionabout the cap axis 201 relative to the viewing angle shown. For example,in some aspects, the torque required to form a seal may naturally placethe vibration sensor 380 (shown in FIG. 5 ) in one of the less desirablepositions, such as position 600 c. In such a case, if the nozzle cap 150is backed off to place the vibration sensor 380 in the desirabletwelve-o-clock position 600 a, the seal between the nozzle cap 150 andthe nozzle 140 a may be compromised, and the nozzle cap 150 can leak.Conversely, a user can attempt to overtighten the nozzle cap 150 towardsthe desirable six-o-clock position 600 e; however, the user may not beable to fully rotate the nozzle cap 150 to vertically align thevibration sensor 380 and achieve optimal signal-to-noise ratio.Additionally, overtightening the nozzle cap 150 can make the nozzle cap150 difficult to remove, such as in the case of an emergency wherefiremen may need to open the nozzle 140 a.

One solution is to alter a gasket thickness T (shown in FIG. 7 ) of thegasket 222 (shown in FIG. 7 ) to adjust the rotational indexing of thenozzle cap 150 relative to the nozzle 140 a. By increasing the gasketthickness T of the gasket 222, the rotational indexing of the nozzle cap150 can be rotated counter-clockwise about the cap axis 201 with respectto the viewing angle shown in aspects wherein the internal threading 218(shown in FIG. 2 ) is right-handed threading. For example, if thevibration sensor 380 (shown in FIG. 7 ) is in position 600 b when thenozzle cap 150 is torqued to the required specification to seal thenozzle 140 a, the nozzle cap 150 can be removed, and the gasket 222 canbe replaced with another gasket 222 having a larger gasket thickness Tso that the vibration sensor 380 can be placed in the twelve-o-clockposition 600 a when the nozzle cap 150 is torqued to the requiredspecification.

Conversely, a thinner gasket 222 can be used to rotate the rotationalindexing of the nozzle cap 150 in the clockwise direction about the capaxis 201 with respect to the viewing angle shown. For example, if thevibration sensor 380 is in position 600 d when the nozzle cap 150 istorqued to the required specification to seal the nozzle 140 a, thenozzle cap 150 can be removed, and the gasket 222 can be replaced withanother gasket 222 having a smaller gasket thickness T so that thevibration sensor 380 can be placed in the six-o-clock position 600 ewhen the nozzle cap 150 is torqued to the required specification.

Rather than changing the gasket thickness T of the gasket 222, similarresults can be achieved by positioning shims between the gasket 222 andthe inner wall 220 (shown in FIG. 2), and a pack of shims of varyingthicknesses can be included with an installation kit for the nozzle cap150. In some aspects, the shim could be attached to the inner wall 220with an adhesive sealant to prevent leaks between the shim and the innerwall 220. In other aspects, two gaskets 222 can be utilized, and theshim can be positioned between the two gaskets 222 to prevent leaksbetween the shim and the inner wall 220. The necessary thickness of theshims can be calculated based on the thread pitch of the internalthreading 218 (shown in FIG. 2 ) using the following formula:

${\frac{\theta}{360 \times {TPI}} = {{Shim}\mspace{14mu}{Thickness}\mspace{14mu}{or}\mspace{14mu}{Change}\mspace{14mu}{in}\mspace{14mu}{Gasket}\mspace{14mu}{Thickness}\mspace{14mu} T}};$wherein θ equals the desired angle of rotational correction in degrees,TPI is the threads-per-inch pitch of the internal threading 218, andshim thickness is measured in inches. For example and withoutlimitation, if the internal threading 218 defines a thread pitch of 5TPI, then each clockwise 360-degree rotation of the nozzle cap 150translates the nozzle cap 150 0.20″ along the cap axis 201 towards thenozzle 140 a. In order to alter the rotational indexing of the nozzlecap 150 counterclockwise by ninety degrees, a 0.05″ shim can be addedbetween the gasket 222 and the inner wall 220. The same formula can beutilized to determine the necessary increase or decrease in gasketthickness T (shown in FIG. 7 ) to achieve the desired rotationalindexing of the nozzle cap 150.

In some aspects of the nozzle cap 150, two vibration sensors 380 can beattached to the nozzle cap 150 at a ninety-degree offset from oneanother along the circumferential wall 312 (shown in FIG. 3 ). In suchan aspect, the nozzle cap 150 would only have to be overtightened orbacked off by a maximum of forty-five degrees to position one of the twovibration sensors 380 in one of the vertical orientations: thetwelve-o-clock position 600 a or the six-o-clock position 600 e. In suchaspects, the nozzle cap 150 can comprise an accelerometer to determinewhich of the two vibration sensors 380 is more optimally oriented whentaking readings. In some aspects, the gasket 222 can comprise a soft,compressive material, such as a soft rubber like neoprene, which canallow for a greater range of adjustment to the rotational indexingcompared to a harder material, such as a hard rubber.

FIG. 7 is a cross-sectional side view of the barrel 120 and nozzle cap150 of FIG. 1 taken along line 7-7 shown in FIG. 6 . In the aspectshown, the vibration sensor 380 can be in the six-o-clock position, andthe sensor axis 301 can be vertically aligned in parallel with thebarrel axis 101. Each of the barrel axis 101 and the sensor axis 301 canbe perpendicular to the cap axis 201.

As shown and previously described, the gasket 222 can define the gasketthickness T, and the gasket 222 can be positioned between the inner wall220 of the cap body 210 and a nozzle end 740 of the nozzle 140 a. Thevibration sensor 380 can also be screwed into the threaded hole 780defined by the circumferential wall 312 to secure the vibration sensor380 to the circumferential wall 312.

In other aspects, the vibration sensor 380 can be positioned within thebonnet 180 (shown in FIG. 1 ) of the fire hydrant 110 (shown in FIG. 1 )or within the barrel 120 (shown in FIG. 1 ) of the fire hydrant 110. Insuch an aspect, the sensor axis 301 can be vertically aligned parallelwith the barrel axis 101 of the barrel 120. Improvement in thesignal-to-noise ratio for the vibration sensor 380 can be attributed toaligning the direction of oscillation of the calibration masses 406(shown in FIG. 4 ) with the direction of vibration propagation. Thecalibration masses 406 can oscillate substantially axially along thesensor axis 301 of the vibration sensor 380. The vibrations canoriginate within the fluid system and then travel substantiallyvertically up the stand pipe 198 (shown in FIG. 1 ) to the fire hydrant110. By vertically aligning the sensor axis 301 parallel to the barrelaxis 101, the calibration masses 406 can be ideally positioned tooscillate upwards and downwards, which makes the vibration sensor 380more sensitive to the vibrations propagating up the stand pipe 198 tothe fire hydrant 110.

During experimentation, vibration sensors were installed on a firehydrant attached to a 6-inch ductile iron water main at a test facility.Vibration sensors were positioned in both vertical and horizontalorientations, and the vibration sensors took readings while water wasflowed from valves to simulate leaks in the water main. Across thefrequency range 0-1200 Hz, the vertically oriented sensor demonstratedan average 3 dB increase in signal strength relative to the horizontallyoriented sensor. Further testing was conducted wherein individualsclapped and yelled in proximity to the fire hydrant to measuresensitivity to airborne background noise, and the vibration sensors inthe vertical orientation were found to be less sensitive to backgroundnoise. Across the frequency range 0-1200 Hz, the vertically orientedsensor demonstrated an average 8 dB increase in signal-to-noise ratiowhen comparing the leak simulation to airborne noise.

Further testing was conducted with fire hydrants to determine if theincrease in signal-to-noise ratio would offer improved performance indetecting leaks. Vibration sensors in both horizontal and verticalorientations were attached to two separate fire hydrants while leaks ofvarying sizes were simulated by opening valves in the attached waterinfrastructure systems. In sixteen out of seventeen conditions tested,the vertically oriented sensors yielded correlations of higher strengththan the horizontally oriented sensors, which demonstrates a higherlikelihood that the vertically oriented sensors would detect the leak ina real world scenario.

One should note that conditional language, such as, among others, “can,”“could,” “might,” or “may,” unless specifically stated otherwise, orotherwise understood within the context as used, is generally intendedto convey that certain embodiments include, while other embodiments donot include, certain features, elements and/or steps. Thus, suchconditional language is not generally intended to imply that features,elements and/or steps are in any way required for one or more particularembodiments or that one or more particular embodiments necessarilyinclude logic for deciding, with or without user input or prompting,whether these features, elements and/or steps are included or are to beperformed in any particular embodiment.

It should be emphasized that the above-described embodiments are merelypossible examples of implementations, merely set forth for a clearunderstanding of the principles of the present disclosure. Any processdescriptions or blocks in flow diagrams should be understood asrepresenting modules, segments, or portions of code which include one ormore executable instructions for implementing specific logical functionsor steps in the process, and alternate implementations are included inwhich functions may not be included or executed at all, may be executedout of order from that shown or discussed, including substantiallyconcurrently or in reverse order, depending on the functionalityinvolved, as would be understood by those reasonably skilled in the artof the present disclosure. Many variations and modifications may be madeto the above-described embodiment(s) without departing substantiallyfrom the spirit and principles of the present disclosure. Further, thescope of the present disclosure is intended to cover any and allcombinations and sub-combinations of all elements, features, and aspectsdiscussed above. All such modifications and variations are intended tobe included herein within the scope of the present disclosure, and allpossible claims to individual aspects or combinations of elements orsteps are intended to be supported by the present disclosure.

That which is claimed is:
 1. A nozzle cap comprising: a cap bodydefining a cap axis, the cap body defining a circumferential wallextending circumferentially around the cap axis; and a vibration sensorcomprising a shaft, the shaft defining a first end and a second end, thefirst end attached to the circumferential wall, the cap axis positionedcloser to the second end than to the first end.
 2. The nozzle cap ofclaim 1, wherein the shaft is defined by a fastener of the vibrationsensor.
 3. The nozzle cap of claim 2, wherein the first end is athreaded end.
 4. The nozzle cap of claim 1, wherein the vibration sensorfurther comprises at least one piezoelectric crystal positioned adjacentto the second end.
 5. The nozzle cap of claim 1, wherein the vibrationsensor further comprises at least one calibration mass positionedadjacent to the second end.
 6. The nozzle cap of claim 1, wherein aspacer is positioned between the first end and the second end.
 7. Thenozzle cap of claim 1, wherein the shaft defines a sensor axis extendingfrom the first end to the second end, and wherein the sensor axisextends radially inward with respect to the cap axis.
 8. The nozzle capof claim 7, wherein the sensor axis is perpendicular to the cap axis. 9.The nozzle cap of claim 1, wherein the circumferential wall defines acavity, wherein the nozzle cap further comprises a printed circuit boardpositioned in the cavity, and wherein the printed circuit board isconnected in electrical communication with the vibration sensor and anantenna.
 10. A hydrant assembly comprising: a fire hydrant comprising abarrel and a nozzle extending outwards from the barrel; and a nozzle capcomprising: a cap body mounted on the nozzle, the cap body defining acap axis, the cap body defining a circumferential wall extendingcircumferentially around the cap axis; and a vibration sensor comprisinga shaft, the shaft defining a first end and a second end, the first endattached to the circumferential wall, the cap axis positioned closer tothe second end than to the first end.
 11. The hydrant assembly of claim10, wherein the shaft is defined by a fastener of the vibration sensor.12. The hydrant assembly of claim 11, wherein the first end is athreaded end.
 13. The hydrant assembly of claim 10, wherein thevibration sensor further comprises at least one piezoelectric crystalpositioned adjacent to the second end.
 14. The hydrant assembly of claim10, wherein the vibration sensor further comprises at least onecalibration mass positioned adjacent to the second end.
 15. The hydrantassembly of claim 10, wherein a spacer is positioned between the firstend and the second end.
 16. The hydrant assembly of claim 10, whereinthe shaft defines a sensor axis extending from the first end to thesecond end, and wherein the sensor axis extends radially inward withrespect to the cap axis.
 17. The hydrant assembly of claim 16, whereinthe sensor axis is perpendicular to the cap axis.
 18. The hydrantassembly of claim 10, wherein the circumferential wall defines a cavity,wherein the nozzle cap further comprises a printed circuit boardpositioned in the cavity, and wherein the printed circuit board isconnected in electrical communication with the vibration sensor and anantenna.